AS was foreseeable and almost inevitable, on November 6, 2014, the Centers for Disease Control and Prevention (CDC) in the USA issued the advisory that doctors in the USA should warn patients travelling to the Caribbean about the outbreak of chikungunya in the region, and should recommend that they take precautions to prevent being bitten by mosquitoes. Additionally, the CDC recommended that US doctors consider chikungunya among the possible diagnoses for patients who have recently travelled to the Caribbean.

The CDC also warned that travellers to the Caribbean, and Central and South America will be at risk for CHIKV infection for the rest of the year, and possibly later. The CDC said it was important that travellers understand the risks and take appropriate actions to prevent mosquito bites. The CDC also informed that the CHIKV outbreak continues to spread throughout the Caribbean.

NEW WEBSITE FOR CHIKUNGUNYA

The Medscape Family Medicine online journal reported that on October 6, 2014, the CDC had unveiled a new website that could help in the fight against the spread of the chikungunya virus and provide information to doctors about the differential diagnosis. The current outbreak, from the first cases that were reported in December 2013 through to October 2014, has so far

caused approximately 795,000 chikungunya fever cases in 37 countries across the Caribbean and in Central, South and North America.

Medscape reported that the number of travellers returning to the USA with chikungunya fever has increased from a yearly average of 28 cases to more than 1,600 from the beginning of the current outbreak in December 2013 through to November 4, 2014. The CDC estimates that approximately nine million people travel between the USA and the Caribbean each year, and so recommended that the best way to protect against chikungunya exposure was for people travelling to use insect repellents and other measures, such as wearing long-sleeved shirts and long pants, and staying in air-conditioned or well-screened rooms at night to help prevent mosquito bites.

DEBILITY CAUSED BY CHIKUNGUNYA

Persons at a high risk for experiencing severe disease from chikungunya infection include those older than 65 years and those persons with co-morbid conditions, such as pre-existing arthritis, hypertension, heart disease, or diabetes. The most common symptoms of chikungunya infection are fever and joint pain, but other symptoms may include myalgia (muscle pain), headache, joint swelling, and rash. While it is not fatal or life-threatening, the joint pain is often severe and debilitating, and may last for much longer that the usual one-week course of the initial illness.

In the past, outbreaks of chikungunya have occurred in countries in Africa, Asia, Europe, and countries in the Indian and Pacific Oceans. However, it was not until the late 2013, that chikungunya was reported in the Caribbean, beginning with the first case in St Martin. Local transmission means that mosquitoes in the area have become infected with the virus, and are spreading it to people. The CDC has confirmed that person-to-person transmission does not occur, and that no vaccine or specific treatment exists. Importantly, however, infected patients are thought to develop lifelong immunity to the particular strain of the virus.

THE NOWCAST TOOL

The CDC has developed the website tool ‘Nowcast’ to help assess how likely were chikungunya-infected travellers to arrive in various cities, and how likely it would be to spread within the USA. Anticipating risks is essential for developing and targeting prevention and control recommendations, with the ultimate goal of helping health departments worldwide make informed decisions about how to reduce the impact of chikungunya in their communities. So far, the number of imported chikungunya cases from infected travellers arriving in the USA has totalled 1,200.

The nowcast website provides estimates of areas in which chikungunya virus activity has most likely occurred in the last month, and then comes up with monthly estimates of when and where chikungunya is most likely to appear next, as well as where infected travellers are most likely to arrive. It looks at variables such as the pattern of existing chikungunya cases, airline flight patterns, and local climate. In the first four months of this year, the model was able to accurately pinpoint eight out of 10 locations that became areas of chikungunya transmission, with this accuracy continuing to date.

For September, the nowcast model indicated an elevated risk for the arrival of infected travellers from other parts of the Americas into the United States, Europe, and into South American countries south of the equator, and so the CDC continues to post travel advisories and regular updates on chikungunya activity.

However, what may be helpful advisories to the US population may be harmful to the welfare of the Caribbean tourism sector.

Derrick Aarons MD, PhD is a consultant bioethicist/family physician, a specialist in ethical issues in medicine, the life sciences and research, and is the Ethicist at the Caribbean Public Health Agency – CARPHA. (The bioethical views expressed here are not written on behalf of CARPHA)